The present invention relates generally to intravenous (IV) catheter assemblies and particularly to increasing the rigidity between a catheter hub and a needle shield of the assembly to facilitate the threading of the catheter.
FIG. 1 illustrates a common IV catheter assembly 100 that consists of a catheter hub 101 and a needle shield 103. Needle shield 103 contains a needle hub from which a needle 102 extends. Needle 102 extends through catheter hub 101 and is used to thread the catheter into the vasculature of a patient. IV catheter assembly 100 is initially handled by a clinician as a single component. The clinician inserts needle 102 into the patient's vasculature and then slides the catheter over top of the needle further into the vasculature. Once the catheter is placed appropriately in the vasculature, needle 102 can be retracted into needle shield 103. Then, needle shield 103 can be detached from catheter hub 101 leaving catheter hub 101 for connection of other devices for blood draw or fluid injection.
Because needle shield 103 and catheter hub 101 are separate components, a certain amount of flexibility may exist between the two components. If this amount of flexibility is too great, the clinician may experience difficulty when inserting needle 102 into the patient's vasculature.
Typically, catheter hub 101 is configured at a proximal end with a connector that is designed to receive a standard connector of another device. For example, catheter hub 101 is often configured to receive a male luer of another device. Because of this, there are limited options for reinforcing the connection between catheter hub 101 and needle shield 103 to limit the amount of flexibility between the components when needle 102 is inserted. Any structural reinforcements must be made in such a way that other devices (e.g. male luers) will still be attachable to catheter hub 101.
Also, many catheter hubs employ a blood control valve that includes components positioned inside of the catheter hub. For example, a catheter hub may include an actuator that is initially positioned near the proximal end of the catheter hub on one side of a septum, and is then forced distally through the septum to open a fluid path through the catheter hub. Because the actuator is positioned near the proximal end of the catheter hub, there is little area for providing structural reinforcements inside the catheter hub.
FIGS. 2A and 2B illustrate an example of a catheter assembly 200 that includes a blood control valve. Catheter assembly 200 includes a catheter hub 201 that employs an actuator 207 and a needle shield 203. Needle shield 203 contains a needle hub 204 which contains a needle 205. Actuator 207 is designed to be forced through septum 206 when another access device is connected to catheter hub 201 to thereby open a fluid pathway through catheter hub 201. Because of the presence of actuator 207 within catheter hub 201, there is little or no additional space within catheter hub 201 into which needle hub 204 could extend.
Also, because actuator 207 is forced through septum 206 by access devices that are connected to catheter hub 201, actuator 207 must have a proximal end that the access devices can press against as the access devices are connected to catheter hub 201. Accordingly, the proximal end of actuator 207 is typically larger in size (e.g. as shown in FIGS. 2A and 2B) which further minimizes the amount of space available at the proximal end of catheter hub 201.
As shown in FIG. 2A, catheter hub 201 and needle shield 203 are connected so that the components are coaxially aligned. In contrast, FIG. 2B illustrates the state of catheter assembly 200 while a clinician is handling the assembly to insert needle 205 into a patient's vasculature. As shown, the clinician typically grips assembly 200 and applies a downward (as represented by the arrow) and forward force to propel needle 205 through the patient's skin. This downward force causes catheter hub 201 and needle shield 203 to flex relative to each other as represented by the dashed line in FIG. 2B.
A substantial amount of flexing may occur because the pivot point between catheter hub 201 and needle shield 203 is formed where the two components connect. Because of this, the primary structure that resists flexing is the portion of needle shield 203 that extends into catheter hub 201. Because this portion is relatively short and thin, it cannot provide significant strength to withstand the flexing forces. As a result, an undesirable amount of flexing often occurs.
The flexing between the catheter hub and the needle shield creates various problems. Primarily, when the components flex, the amount of force transferred to the needle is reduced thereby making it more difficult to insert the needle through the patient's skin. Also, when this flexing occurs, the clinician perceives the components as being weak which may cause the clinician to alter the catheter insertion procedure or to view the catheter assembly as being unsatisfactory. In some cases, this flexing may also lead to failure of the components.